Nonsettling mineral fillers



Patente d'Aug. 19, 1947 UNITED STATES PATENT OFFICE nonsn'rrrmo MINERALFILLERS Armand R. Bollaert, Palos Verdes, Calif., assignor to GreatLakes Carbon Corporation, a corporation of Delaware No Drawing.Application October 15, 1945, Serial No. 522,477

8 Claims. (01.106-288) This invention relates to the treatment ofmindiate layer of slurry of variable consistency, and

a hard and compact bottom layer. In extreme cases, as after longstanding, the intermediate layer may be missing.

If the hard lower layer can be prevented from forming, the partialsedimentation which produces a concentrated slurry is harmless as thisslurry, even if very thick, may readily be redispersed by simplestirring. The formation of a hard layer, however, is highlyobjectionable. Such sediments, formed in a stored package, are tediousand diflicult to again bring into suspension and are likely to result inlumping. Where such hard layers form in mixing vessels or tanks theapparatus may have to be cleaned out before it can again be put intooperation. 1

I have discovered that the formation. of compact settled layers may beprevented, and sedimentation restricted to the formation of a thickslurry, by mixing with the filler a small proportion of a highlycolloidal clay, such as the socalled bentonite, together With a minuteproportion of a salt of ammonium with a mineral acid. These admixturesdo not prevent sedimentation of the filler but, when used in suitableproportions, they maintain the settled layer in the soft and uncompactedcondition in which it may readily be redispersed.

In order to determine the effectiveness of the treatment, the optimumdosages of the agents and the specific ammonium salts most efiective forthe purpose, experiments were conducted with a diatomaceous earth fillerconsisting of the fines from the manufacture of high quality filter-aidsby calcination with fiuxing agents. This material settles rapidly fromaqueous suspension to form hard layers which are very dilficult to bringback into suspension.

In these experiments, grams of the filler was dispersed in 100 ml.water, with or without the addition of one or more of the agents namedin the table below. The suspensions were then allowed to standundisturbed for eight days, after which an arbitrary measurement of thesolidity of the settledlayer was made by allowing a glass rod of 4'diameter and weighing 46 grams to subside to constant level through it.As the diameters of the cylinders in which the tests were made variedslightly, the measurement made was of the percentage of the total volumeoccupied by the layer sufiiciently solid to support the rod. As thisfigure is entirely arbitrary and useful only for comparison, numerouscheck experiments were made which showed that if this supporting volumedid not exceed 14% of the total volume the settled layer could beredispersed without material dimculty, and that the difiicultyexperienced in redispersion increased as this percentage volumeincreased.

Ammonium chloride and Wyoming bentonite were added to this suspension inthe proportions set forth below, withthe following results:

Table 1 Composition in Grams Volume of Supporting Filler BentoniteChloride Layer Per cent 10 l. O 0. 1O 0 10 1. 0 0. 06 11 10 1. 0 0. 0516 10 1. 0 O. 04 16 1O 1. 0 0. 03 18 10 1. 0 0.02 18 10 1. 0 0. 00 l8 l00. 0 O. 00 21 10 l. 5 0. 06 0 10 l. 0 0. 06 l1 10 0.8 0.06 21 10 0. 60.06 21 10 0. 4 O. 06 21 10 0. 0 0. 06 21 It will be noted that thesepercentage figures are good only for this particular filler and do notshow the same critical limits when other fillers are substituted fordiatomaceous earth.

When other ammonium salts were substituted for the chloride, in constantproportions, the following results were obtained:

Table 2 Composition in Grams Volume Ammonium Salt of Sup- I Used portingFiller Bentomte Salt Layer Per cent 10 1. 0 0. 05 Sulfate 0 10 1.0 0. 06Chloride. ll 10 1. 0 0. 06 Phosphate 14 10 1. 0 0. 06 Acetate 17 10 1. 00.06 Carbona 19 10 1. 0 0. O6 Oxalate... 19 10 l. 0 0.06 Hydroxide.-.-20

The figures in these two tables show that neither bentonite alone northe ammonium salt alone produce any material improvement in permanenceand that they function together to produce the desired result. They alsoindicate a satisfactory stabilization of the suspension when thebentonite component is about 10% of the weight of filler taken and theammonium chloride about 1%; of 1% of that weight. They also show perfectsuspension when ammonium sulfate is substituted for the chloride in theabove proportions, or when the proportion of chloride is raised to about1% (with bentonite) or when the proportion of bentonite is raised toabout (-with 0.6% chloride). Finally, they indicate that satisfactoryresults are obtained only in the use of the ammonium salts of the strongmineral acids such as hydrochloric, sulfuric and phosphoric.

I claim as my invention:

1. A stabilized aqueous suspension of finely comminuted diatomaceousearth containing from 10 percent to 15 percent of a colloidal bentoniteand from 0.6 percent to 1.0 percent of an armmonium salt of a strongmineral acid, said percentages being on the dry weight of earth in saidsuspension.

2. A stabilized aqueous suspension of finely comminuted diatomaceousearth containing from 10 percent to 15 percent of a colloidal bentoniteand from 0.6 percent to 1.0 percent of ammonium chloride, saidpercentages being on the dry weight of earth in said suspension.

3. A stabilized aqueous suspension of finely comminuted diatomaceousearth containing from 10 percent to 15 percent of a colloidal bentoniteand from 0.6 percent to 1.0 percent of ammonium sulfate, saidpercentages being on the dry weight of earth in said suspension.

4. A stabilized aqueous suspension of finely comminuted diatomaceousearth containing from 10 percent to 15 percent of a colloidal bentoniteand from 0.6 percent to 1 percent of ammonium phosphate, saidpercentages being on the dry weight of earth in said suspension.

5. A mineral filling and bodying agent characterized by settling fromaqueous suspension to form a oft and readily dispersi-ble mass,consisting substantially of 100 parts of finely comminuted diatomaceousearth, from 10 parts to 15 parts of a colloidal bentonite, and from 0.6part to 1 part of a salt of ammonium with a strong mineral acid, allsaid parts being by dry weight.

6. A mineral filling and bodying agent characterized by settling fromaqueous suspension to form a soft and readily dispersible mass,consisting substantially of parts of finely comminuted diatomaceousearth, from 10 parts to 15 parts of a colloidal bentonite and from 0.6part to 1 part of ammonium chloride, all said parts being by dry weight.

7. A mineral filling and bodying agent characterized by settling fromaqueous suspension to form a soft and readily dispersible mass,consisting substantially of 100 parts of finely comminuted diatomaceousearth, from 10 parts to 15 parts of a colloidal bentonite and from 0.6part to 1 part of ammonium sulfate, all said parts being by dry Weight.

8. A mineral filling and bodying agent characterized by settling fromaqueous suspension to form a soft and readily dispersible mass,consisting substantially of 100 parts of finely comminuted diatomaceousearth, from 10 parts to 15 parts of a colloidal bentonite and from 0.6part to 1 part of ammonium phosphate, all said parts being by dryWeight.

ARMAND R. BOLLAERT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,016,892 Clarvoe Oct. 8, 19352,266,793 Opperman Dec. 23, 1931 1,738,967 Sadtler Dec. 10, 19291,758,145 'Clutterbuck Ma 13, 1930 2,366,047 Ner-linger Dec. 26, 1944OTHER REFERENCES Natural Mineral Paint Extenders, by Charles T. Harness.

National Paint Bulletin, June 1945, page 6.

